a Family of the Hymenoptera Heterogyna. 271 



and which become corroborated, as I observe above, by the form of 

 the male sexual apparatus. The species in the present genus 

 seem to separate themselves into groups, for there is less uniformity 

 of general structure than is commonly found in a natural genus, and 

 the form of the peduncle of the abdomen appears in some degree to 

 influence the form of other parts. The groups they resolve them- 

 selves into are these, which may be thus characterized by the form of 

 the peduncle alone or in conjunction with the mandibles, viz. : 



1st. Peduncle cup-shaped, nearly as large as the following segment* 



Sp. 1. 



2nd. Peduncle cup-shaped, much smaller than the 2nd segment. 



Sp. 2. and 3. 



3rd. Peduncle quadrate, mandibles slender and much acuminated. 



Sp. 4, 5, 6. 



4th. Peduncle quadrate, mandibles broad and nearly triangular. 



Sp. 7, 8, 9, 10. 



Sp. 1. Dor. nigricans, IUiger. Length 13 lines. 



Expansion 21 ^ lines. 

 Nigricans, brunneo-holosericeus y abdominis petiolo acetabidiformi, segmento 

 secando paulo minor. 



IUiger, Mag. der Ent. l ter . Bd. Seit. 188. 18. 

 Fabricius, System. Piez. 427. 2. 

 Latreille, Gen. Crust, et Ins. 4. 124. 



, Nouv. Diction. d'Hist. Nat. 2 e ed. 9. 556. 



Blackish brown, velvety, elongate cylindrical : head comparatively large, 

 slightly convex towards and beneath the vertex ; the ocelli are compa- 

 ratively small and are placed in a triangle ; eyes lateral, small, ovate 

 convex : antennae short, setaceous, the scape rather more than one- 

 third the length of the organ ; mandibles elongate, narrow, much acu- 

 minated, and with the antennas and legs of a dark castaneous. 

 Thorax very robust, covered with a bright brown silky pubescence, with two 

 abbreviated longitudinal central lines in front : scutellum slightly gib- 

 bous, broad : superior wings with their nervures blackish, and the sur- 

 face clouded with brown, the recurrent nervure inserted just within 

 the centre of the second submarginal cell, the cubital nervure extend- 

 ing straight to the angle of the second submarginal : femora elongate, 

 triangular, subacuminate at the apex. 

 Abdomen cylindrical, blackish brown, the margins of the segments a little 

 paler : the peduncle cup-shaped above, villose beneath, nearly as large 

 as the second, the terminal smooth and abruptly truncated at its ex- 

 treme apex, which is a little reflected. In most Collections. 

 This remarkable species, which in the size of its head and peduncle 

 and smallness of its eyes differs from all its congeners, is from Sierra 



Leone. 



[To be continued.] 



